1. Field of the Invention
The present invention relates to an electronic component module wherein circuit components including an oscillation circuit are mounted on a circuit substrate, and the present invention also relates to a piezoelectric oscillator device including such an electronic component module.
2. Description of the Related Art
Portable telephone terminals now require miniaturization, and the quartz oscillator device for generating the reference oscillation signal used in the portable telephone terminal also requires a reduction in size and thickness. As the quartz oscillator device used in a conventional portable telephone terminal, a surface-mounting type structure as shown in FIG. 6, has been disclosed to meet such a request for reduction in the size and thickness. This quartz oscillator device 31 includes circuit components 33 including an oscillation circuit, a temperature compensation circuit, and other suitable components, are surface-mounted on a box-shaped circuit substrate 32 defined by ceramic multi-layered substrates, and wherein a quartz vibrator package 34 accommodating a quartz member is stacked on the circuit substrate 32 to define a lid.
In a quartz oscillator device as described above, in order to meet the request for reducing thickness and size, the depth of the recess in the circuit substrate is determined in accordance with the most high-profile component in the circuit components, and the thickness of the bottom plate is determined so as to have the minimum strength required. Also, by using the ceramic material having a high strength for a circuit substrate, the thickness of the bottom plate of the circuit substrate is reduced, and the overall thickness of the quartz oscillator device is reduced.
However, although the thickness of the quartz oscillator device can be reduced by reducing the thickness of the bottom plate of the recess in the circuit substrate, the thinner the bottom plate of the recess in the circuit substrate becomes, the lower the strength of the circuit substrate becomes. This causes the circuit substrate to be prone to cracking due to shock produced when circuit components are mounted thereon, or causes the circuit substrate to be prone to warping when the circuit substrate is baked. This reduces the yield of quartz oscillator devices when they are mass-produced.
To overcome the above-described problems, preferred embodiments of the present invention solve the problems with the above-described conventional art and greatly improve the yield when electronic component modules or piezoelectric oscillators are mass-produced, by providing a margin of strength for each of the substrates thereof while greatly reducing the thickness of the electronic component modules.
Preferred embodiments of the present invention provide an electronic component module including a circuit substrate, and a recess provided in the top surface of the circuit substrate, the recess being defined by a plurality of regions where the thicknesses of the bottom plates thereof differ from one another, and the recess including at least one portion where the circuit components are mounted on the circuit substrate.
In an electronic component module in accordance with preferred embodiments of the present invention, the bottom of the recess of the circuit substrate is defined by a plurality of regions where the thicknesses of the bottom plate thereof differ from one another. Hence, by mounting low-profile components on the region where the thickness of the bottom plate is larger, and by mounting high-profile circuit components on the region where the thickness of the bottom plate is smaller, the region where the thickness of the bottom plate is smaller is restricted to only the region that is actually required. This permits the thickness of the bottom plate of the recess to be partially thick, or permits the area of the region where the thickness of the bottom plate is smaller to be greatly reduced, which results in a greatly enhanced bending strength of the circuit substrate. Furthermore, the shock strength, and the mechanical-stress resistance in working processes of the circuit substrate is greatly improved, and enables the yield of electronic component modules to be greatly increased.
A preferred embodiment of the present invention provides an electronic component module including a plurality of recesses, each preferably having an insular shape on the top surface of the circuit substrate, and each accommodating a circuit component.
In an electronic component module in accordance with preferred embodiments of the present invention, since the recesses for accommodating circuit components include a plurality of islands, the space within the circuit substrate is greatly reduced, and even if the thickness of the bottom plate is decreased, the area of the portion where the thickness of the bottom plate is small, is greatly reduced. As a result, the bending strength, the shock strength, and the mechanical-stress resistance in working processes, of the electronic component module is greatly enhanced, and thereby the yield when electronic component modules are mass-produced is greatly improved.
Preferably, at least one portion of the plurality of recesses has a different depth from other recesses.
Moreover, in an electronic component module in accordance with a second preferred embodiment of the present invention, since the thickness of the bottom plate of the recess is determined in accordance with the height of each of the circuit components accommodated in the recess, the thickness of the bottom plate of the recess accommodating a low-profile circuit component is greatly increased. This permits the bending strength, the shock-resistance, and the mechanical-stress resistance in working processes of the circuit substrate is further enhanced.
Preferably, the top surfaces of the circuit components mounted in the recess is arranged to be substantially flush with the top surface of the circuit substrate.
Furthermore, in an electronic component module in accordance with the second preferred embodiment of the present invention, since the top surfaces of the circuit components are substantially flush with the top surface of the circuit substrate, wasted space over the circuit components is eliminated, and thereby the thickness of the bottom surface plate is greatly increased, and the overall thickness of the electronic component module is greatly reduced. Also, when circuit components are mounted face down, the top surfaces of the electrodes of all circuit components are substantially flush with one another. This facilitates the wiring of the circuit.
Other preferred embodiments of the present invention provide a piezoelectric oscillator including at least an oscillation circuit defined by the above described electronic component module, and including a vibrator package accommodating a piezoelectric member, the vibrator package is stacked on the electronic component module, and the vibrator package is thereby integrated with the electronic component module.
In an electronic component module in accordance with a preferred embodiment of the present invention, the thickness of the piezoelectric oscillator is greatly reduced by stacking an vibrator package on the electronic component module in accordance with a preferred embodiment of the present invention, and the bending strength, the shock strength and the mechanical-stress resistance in working processes of the piezoelectric oscillator are greatly enhanced, which results in a substantial improvement in the yield when the piezoelectric oscillators are mass-produced.
Meanwhile, the electronic component module is not limited to the circuit substrate on which the oscillation circuit of a piezoelectric oscillator is mounted. Any circuit substrate which has a circuit defined by a plurality of circuit components provided thereon may be used.
Other features, elements, characteristics and advantages of the present invention will become more apparent from the detailed description of preferred embodiments below with reference to the attached drawings.